I used to have a 4runner and was a member of a Hilux forum, there was a member on there called Suprux, yeah it was an older Hilux with 3ltr Supra straight six, howled like a banshee and fried tyres (4 wheel) the amount of work to get it done was alarming and it was prone to breaking stuff.
The motor barely fitted, it had no fan or water pump on the front, the radiator was in front of the apron with twin thermo's pushing from the outside and an inline pump to push the coolant, theres more to it as I'm just trying to recall from quite a while back.
Doable yes, worth the heartache no, oh and it had **** economy of course.